Muscle physiology and muscle pathologies are important research subjects under the missions of ICs such as NIAMS and NHLBI. In a continuing collaboration with NIAMS researchers, atomic force microscopy (AFM) and related biophysical methods are being applied to investigate muscle proteins such as titin (a massive peptide chain of 3-4 MDa) and nebulin (600-900kDa). The work includes coauthoring a comprehensive review of AFM and laser optical trap (LOT) nanotechnologies as applied to titin research and the resulting understandings on titin biophysical properties and implications for muscle physiology and pathology. AFM measurements and interpretations of the molecular elasticity of a titin motif, termed PEVK region, is also continuing. AFM investigations of nebulin structure and modular folding energetics and data interpretations and AFM instrument advancement are other areas of activity and achievements.